This application addresses the ongoing need at Johns Hopkins University (JHU) for high-speed cell sorting of specimens infected with organisms which are biohazardous to humans. It requests support to upgrade a Beckman Coulter MoFlo Legacy flow cytometer, housed in a biosafety level 3 (BSL3) laboratory in the Johns Hopkins Bloomberg School of Public Health, to the functional equivalent of a MoFlo XDP flow cytometer. The MoFlo Legacy cytometer in question is more than 11 years old, is tenuous as a critical instrument to support a large number of research projects that depend on it (specifically projects in the areas of HIV/AIDS, cancer, neurodegenerative diseases, and other diseases of human cells where sorting in a protected environment is appropriate), and will no longer be supported by the manufacturer as of late 2013. As most cell sorting facilities at JHU refer to us the sorting of human samples that may contain agents such as hepatitis viruses or other pathogens, and our laboratory is the main biosafety level 3 (BSL3) cell sorting facility at JHU, a reliable and adequately sophisticated sorter is critical for the continued success of this facility, which has contributed data to at least 70 publications, including important advances in understanding and care of HIV infection, since the acquisition of the current cytometer. The laboratory team is well experienced in management of a BSL3 core facility, with the principal investigator of this application having directed this facility since 1989. With the current MoFlo cytometer now reaching its life expectancy, upgrading and modernizing it are a) needed to sustain and expand the current scale of research, and b) much more cost-effective for this purpose than purchasing a new sorting cytometer. Among the HIV-related research areas that depend on this facility are understanding the generation and possible mechanisms of eradication of HIV reservoirs in vivo, immune pathogenesis of HIV infection, and pathogenesis of HIV-related infections. Other areas of human investigation include pathogenesis of neurological disease, role of stem cells in cancer and other diseases, and aspects of gene regulation in many human diseases. Specific research projects of 5 major investigators and numerous other users of the core that would benefit from continued availability and reliability of this facility are described, as are the specific features of the MoFlo upgrade that justify its acquisition. Many other projects would also use the new sorter over its lifetime. Procedures and plans for sustaining the cell sorting facility's ability to support HIV and human research at JHU for the future are described, as are financial plans for operation of the facility including institutional support comprised of covering the service contract for the upgraded cytometer and any financial shortfalls that may develop. The facility will be operated by an experienced full-time cytometer operator and a new operator to be trained and supervised by the facility director, with oversight by an internal advisory committee. With the requested upgrade, the facility will continue to make unique contributions to the treatment, management, and prevention of HIV infection and other human diseases for many years.